Microsoft took a bold step into the tablet market on Monday with the unveiling of a computer aimed squarely at bettering Apple's market-leading iPad.

The computer, called Surface, will be available in two versions. One will run the Windows 8 Pro operating system and the other will be based on Windows RT, a new version of Windows designed to run on the ARM family of processors that are predominant in the tablet market.

"It's something new, something different, a whole new family of computing devices from Microsoft," said Steve Ballmer, CEO of Microsoft, at a Los Angeles news conference.

The Microsoft Surface tablet, unveiled late on Monday, comes with a built-in "kickstand."

The machine has a 10.6-inch, widescreen, high-definition display and comes with a 3-millimeter-thick, pressure-sensitive cover that doubles as a keyboard.

Current specifications call for the Windows RT version to be slightly thinner but slightly heavier than Apple's latest iPad, although Microsoft notes the size and weight of the device could change once mass production begins.

The Windows 8 Pro version will be thicker and heavier and appears designed to compete with ultra-thin notebook computers. It should be able to run all the same software as those computers.

Microsoft revealed a few basic specifications for the tablets. The RT version will come with 32 or 64 gigabytes of storage, while the Windows 8 Pro version will have 64 or 128GBs.

Microsoft didn't provide exact prices or launch dates for the tablets but said the RT version would be priced comparable with competing ARM-based tablets and be available around the time of the launch of Windows 8. The Windows 8 Pro will follow about three months later and cost around the same as ultrabook notebook computers.

By producing its own hardware, Microsoft will be navigating a tricky course as the computers will be in direct competition with companies such as Asus, Lenovo and Samsung, with whom it maintains strong partnerships for development of tablets and laptops.

"With Surface, Microsoft has just made it even harder for every ODM [original design manufacturer) out there to compete in the tablet market -- aside from Apple, that is," said Carolina Milanesi, research VP at Gartner.

The device was unveiled at a Los Angeles news conference that saw Microsoft apparently copying a page from Apple's product launch playbook. Gambling that its status and the promise of "major" news would be enough, Microsoft managed to attract around 300 reporters to the event despite providing no advance details of the nature of the news and not even disclosing the location of the announcement until Monday morning.

The tactics worked as business and tech media spent the weekend and much of Monday engaged in speculation on what Microsoft would be announcing and the term "MSMajorAnnouncement" entered Twitter's global list of trending topics an hour before the announcement.

Microsoft has had mixed success marketing its own hardware. While devices like the Zune music player and Kin smartphone received similar high-profile launches and were ultimately discontinued, the company has had considerable success with the Xbox gaming platform.

The global tablet market, which includes devices such as the iPad, Amazon Fire and Barnes & Noble Nook, is expected to roughly double this year to 119 million units, according to an estimate from Gartner. Next year will see a further 63 million units shipped to take the worldwide market to $182 million, Gartner said.

Announcement of the device comes 12 years after Microsoft first started pushing the concept of tablet computing. Then-chairman Bill Gates showed off a prototype tablet PC at the Comdex 2000 trade show but it wasn't until Apple launched the iPad in 2010 that the market began to take off.